Cylinder-head gasket comprising an edge-to-edge stop ring

ABSTRACT

The invention concerns a head-cylinder gasket with at least an opening ( 14 ) corresponding to a combustion chamber, comprising a so-called outer plate ( 12 ) including a circular rib ( 16 ), surrounding the opening ( 14 ), arranged at a distance d from the edge of said opening ( 14 ), and a support plate ( 18 ) arranged against the surface of the outer plate ( 12 ) bearing the rib ( 16 ) in projection, including an opening with a diameter larger than the opening ( 14 ) of the outer plate so as to define a space wherein is arranged a stop ring ( 20 ) in the form of an annular wedge with an internal diameter corresponding to that of the opening ( 14 ) and an external diameter substantially adjusted to the opening of the support plate so as to be arranged edge-to-edge. The invention is characterised in that it comprises an element ( 24 ) interposed between the stop ring ( 20 ) and the support plate maintaining said stop ring.

The present invention relates to a gasket, particularly a cylinder headgasket comprising an edge-to-edge stopper. More particularly, thepresent invention concerns a multisheet head gasket comprising at leasttwo sheets of which at least one is ribbed.

According to one embodiment, the head gasket comprises two sheets withat least one opening corresponding to the opening of a combustionchamber, at least one of the two sheets, and preferably both, comprisinga rib disposed around each opening at a distance from the edge of saidopening, said ribs being deformed toward the interior of the gasket.

In addition, the gasket comprises an intermediate support sheetinterposed between the two external sheets and opposite the ribs as wellas a stopper in the form of an annular lining having an internaldiameter approximately corresponding to that of the opening and anexternal diameter smaller than that of the ribs, said stopper beingdisposed edge-to-edge along the extension of the support sheet.

The connection between the stopper and the support sheet is generallymade by welding, gluing or the like. French patent applicationFR-00.12669 filed in the name of Applicant proposes a process for fixingthe stopper to the support sheet by radial expansion of said stopper.

The present invention proposes a novel cylinder head gasket comprisingan edge-to-edge stopper with a new stopper/support sheet connection thatprovides better support for said stopper.

To this end, the object of the invention is a cylinder head gasket withat, least one opening corresponding to a combustion chamber andcomprising, on the one hand, at least two external sheets of which atleast one comprises a circular rib that surrounds the opening and isdisposed at a distance d from the edge of said opening and, on the otherhand, a support sheet disposed between the external sheets and having anopening with a diameter that is greater than the opening of the externalsheets so as to define a space wherein is disposed a stopper in the formof an annular lining with an internal diameter corresponding to that ofthe opening and an external diameter approximately adjusted to theopening of the support sheet so as to be disposed from edge to edge,characterized in that it comprises an element interposed between thestopper and the support sheet to ensure the support of said stopper.

According to one embodiment, the element interposed between the stopperand the support sheet is in the form of a rivet provided at each endwith a border folded down against the faces of the support sheet and thestopper so as to grip them and to limit their relative movements.

Advantageously, the stopper comprises at its periphery at least one tabat the level of which is disposed the support element.

According to another embodiment a forced-in pin is interposed by forcebetween the stopper and the support sheet.

Other features and advantages will become apparent from the followingdescription of the device of the invention, the description beingprovided only as an example and referring to the drawings attachedherewith in which:

FIG. 1 is a plan view in cross-section of the support sheet of amonocylinder head gasket according to the invention,

FIG. 2 is a plan view in cross-section of the support sheet of amulticylinder head gasket according to a first variant of the invention,

FIG. 3 is a plan view in cross-section of the support sheet of amulticylinder head gasket according to another variant,

FIG. 4 is a top view in elevation of a cylinder head gasket according tothe invention, and

FIG. 5 is an enlarged cross-sectional view along line V-V of FIG. 4.

In the drawings is shown a cylinder head gasket 10 comprising at leastone external sheet 12, and preferably two as illustrated in FIG. 5, withat least one opening 14 corresponding to a combustion chamber of anengine block, at least one of the external sheets 12, and preferablyboth, comprising a circular rib 16 that surrounds opening 14 and isdisposed at a distance d from the edge of opening 14, the rib or ribsbeing deformed toward the inside of the gasket.

In a known manner, the intermediate support sheet 18 is interposedbetween the external sheets 12. In the case where the gasket containsonly one external sheet 12, the support sheet 18 is disposed against theface of the external sheet 12 on which is provided the protruding rib.

The support sheet comprises an opening that is concentric with opening14 of the external sheet or sheets 12 and has a diameter greater thanopening 14 so as to define a space wherein is disposed stopper 20 in theform of an annular lining and having an internal diameter correspondingto that of opening 14 and an external diameter approximately adjusted tothe opening of the support sheet.

Said stopper comprises at least one zone 22 of thickness X1 greater thanthickness X2 of the support sheet so as to constitute a limiter againstthe crushing of the ribs, a first tightness barrier, and to permit thearching of at least one external sheet 12 so as to limit the deflectionsof the said sheet during operation.

Depending on the case, the external diameter of stopper 20 can besmaller than that of ribs 16 so that support sheet 18 fits between ribs16, or it can be greater than that of ribs 16 so that a zone of saidstopper of thickness less than X1 fits between ribs 16 as illustrated inFIG. 5.

The advantage of said last variant is that a piece of relatively highaccuracy, the stopper being perfectly calibrated, fits between ribs 16which results in a reduced intercylinder distance between openings 12because of the fact that only stopper 20 is disposed between saidopenings 12.

Stopper 20 can be of the metallic type or made of fibrous material asdescribed in patent application FR-01.06129 filed in the name ofApplicant.

According to another feature, the stopper can have a tapered profilealong its periphery. Thus, its thickness can be varied so as to obtain aconstant contact pressure in spite of localized compressive forces.

According to the invention, stopper 20 is connected to the support sheet18 by an element 24 that is interposed between said pieces.

Preferably, element 24 has a cylindrical shape like a pin or a rivet andis distinct from the stopper and the support sheet.

According to a preferred embodiment illustrated in FIG. 5, one orseveral rivets of the open type, known as eyelets, are used, said rivetshaving at each end a rim 26 which is folded against the faces of supportsheet 18 and stopper 20 gripping them.

In this case, it is not necessary to use force to push the rivet orrivets between stopper 20 and support sheet 18, these elements beingconnected to each other by rims 26 that limit the relative movementsbetween these two elements 18, 20.

This design allows one to obtain a stopper/support sheet connection thatis less rigid than the prior-art designs based on welding or gluing andimproves the operation of the cylinder head gasket. This arrangementpermits the stopper to move relative to the other sheets thus permittingthe gasket better to adapt itself to the compressive forces thatinevitably are different depending on the zones considered.

According to a first variant illustrated in FIGS. 1, 2 and 4, rivet 24is disposed directly between stopper 20 and support sheet 18 without theprofile of these two elements being modified in any way.

According to a second variant illustrated in FIG. 3, rivet 24 isdisposed at the level of a tab 26′ provided at the periphery of stopper20. The main advantage of said tab 26′ is that rotation indexing ofstopper 20 is obtained relative to the remainder of the gasket,particularly when said gasket has a tapered profile along itscircumference. It will be understood that other indexing means can beused in place of the tabs to position the stopper by rotation.

Moreover, this arrangement provides greater amplitude of movement ofstopper 20 relative to support sheet 18 thus improving the efficacy ofsaid stopper.

In all cases, the thickness of rivet 24 is less than the total thicknessof the cylinder head gasket, and apertures 28 are provided at the levelof external sheets 12 opposite rivets 24 so that the assembly does notinterfere with the proper functioning of the gasket.

The number of rivets needed to support the stopper will be chosen bythose skilled in the art so as to ensure proper support for stopper 20.

For a simple ring, it will preferably be necessary to provide twodiametrically opposed rivets.

In the case that the stoppers are connected to each other in anintercylinder zone as illustrated in FIGS. 2 and 3, one rivet percylinder can suffice, the rivets being disposed in a staggered fashion.

According to another variant, element 24 that is interposed betweenstopper 20 and support sheet 18 can be in the form of a pin forced in toensure a firm connection between the stopper and said sheet.

It will be understood that the invention is obviously not limited to theembodiments described hereinabove, but that, on the contrary, it coversall variants, particularly those concerning the profile of the stopper,the materials used, the fabrication of the sheets, each of which canconsist of a stack of sheets, and the profiles and positions of theribs.

1. Cylinder head gasket with at least one opening (14) corresponding toa combustion chamber and comprising, on the one hand, a sheet (12)referred to as the external sheet and comprising a circular rib (16)that surrounds the opening (14) and is disposed at a distance from theedge of said opening (14) and, on the other hand, a support sheet (18)disposed against the face of the external sheet (12) bearing theprotruding rib (16) and comprising an opening of diameter greater thanthe opening (14) of the external sheet so as to define a space withinwhich is disposed a stopper (20) in the form of an annular lining havingan internal diameter that corresponds to that of the opening (14) and anexternal diameter approximately adjusted to the opening of the supportsheet so as to be disposed from edge to edge, characterized in that saidcylinder head gasket comprises an element (24) that is interposedbetween the stopper (20) and the support sheet ensuring the support ofsaid stopper.
 2. Cylinder head gasket with at least one opening (14)corresponding to a combustion chamber and comprising, on the one hand,at least two sheets (12) referred to as the external sheets at least oneof which comprises a circular rib (16) that surrounds the opening (14)and is disposed at a distance from the edge of said opening (14) and, onthe other hand, a support sheet (18) disposed between the externalsheets (12) and comprising an opening of a diameter greater than theopening (14) of the external sheets so as to define a space wherein isdisposed a stopper (20) in the form of an annular lining having aninternal diameter that corresponds to that of the opening (14) and anexternal diameter approximately adjusted to the opening of the supportsheet so as to be disposed from edge to edge, characterized in that saidcylinder head gasket comprises an element (24) that is interposedbetween the stopper (20) and the support sheet ensuring the support ofsaid stopper.
 3. Cylinder head gasket according to claim 1 or 2,characterized in that the element (24) interposed between the stopper(20) and the support sheet (18) is in the form of a rivet comprising ateach end a rim (26) folded against the faces of the support sheet (18)and the stopper (20) so as to grip them and to limit their relativemovements.
 4. Cylinder head gasket according to claim 3, characterizedin that an aperture (28) is provided at the level of the external sheetor sheets (12) opposite each rivet (24).
 5. Cylinder head gasketaccording to claim 3 or 4, characterized in that the thickness of therivet (24) is less than the total thickness of the cylinder head gasket.6. Cylinder head gasket according to any one of claims 1 to 5,characterized in that the stopper (18) [sic—“(20)” seems to bemeant—Translator] comprises at the periphery thereof at least one tab(26′) at the level of which is disposed the support element (24). 7.Cylinder head gasket according to claim 1 or 2, characterized in that aforced-in pin is interposed between the stopper (20) and the supportsheet (18).